Testing filters and selecting respirators for control of infectious aerosol exposures.

摘要

This research addressed three aspects of respiratory protection as a means of controlling exposures to infectious aerosols: the performance of respirator filters when challenged with aerosolized bacteria, the fate of the collected organisms, and selection of the proper respirator.; The collection efficiency of surgical masks and NIOSH-approved respirator filters was evaluated through challenge with a non-biological aerosol and three aerosolized bacteria (Mycobacterium abscessus, Staphylococcus epidermidis, and Bacillus subtilis). Masks and filters were tested with a 0.55 {dollar}mu{dollar}m polystyrene latex sphere aerosol at 45 L/min and 50% RH. Bioaerosol challenges were carried out at two flows (45 and 85 L/min) and two relative humidity conditions (30 and 70%).; The collection efficiency of filters challenged with the biological aerosol was found to be correlated with that of filters challenged with non-biological aerosols. Additionally, changes in test conditions produced expected changes in efficiencies. These findings indicate that it is the physical, rather than the biological, characteristics of the organisms which govern filter collection. Therefore, current National Institute for Occupational Safety and Health respirator filter certification tests which use non-biological aerosols are relevant to biological aerosols.; Following bioaerosol challenge tests, viable organisms were recovered from the filter using elution and surface sampling. The unsampled portion of the filter was stored for five days at 85% relative humidity and organisms were again recovered using the same methods. All three organisms were found to survive on the filter media after storage. These results should be considered when setting respirator reuse, handling, and disposal protocols.; Finally, a process was developed for selecting respirators to control exposures to infectious aerosols. The traditional industrial hygiene respirator selection method served as the basis for this proposal; modifications were made for situations in which data on occupational exposure limits, toxicity, and concentrations are lacking.; This research contributed knowledge about the control of infectious aerosols which will allow health and safety personnel to make more informed decisions in real-life settings. Since the current filter certification tests are relevant to infectious aerosols, respirators approved by these methods can be properly selected and appropriately used for such exposures.